How ancient Puebloan societies built resilient, sustainable cities in extreme climates—lessons for modern living without relying on 24/7/365 climate control via HAVC.
You know a place has excellent weather when three or four days straight in the low-90s Fahrenheit (slightly over 30 degrees Celsius) and low humidity are considered a legit heat wave, requiring the suspension of children’s sports and a series of daily heat-warning messages.
The Bay Area, a place with a truly mild climate all year round and more gentle Mediterranean weather than most of the north shore of the Mediterranean Basin, just experienced a few days of relative “heat.” Yet I exercised and used the bicycle as usual, seeing no one struggling with the temperatures outside.
In the context of the damage caused recently by Hurricane Helene in Appalachia and Hurricane Milton in Florida, as I write this, there was no such thing as a weather emergency in the Bay Area lately, just a few warm-ish days. This reminds us of how much the local zeitgeist depends on local standards: if it always feels between 65- and 75-degrees Fahrenheit, anything about 80 is “heat.”
Places like Silicon Valley, most of the East Bay, San Francisco, and most of Marin County experience a microclimate that could only be improved with less morning fog. San Luis Obispo in Central California is perhaps the perfect weather—or San Francisco weather with fewer chilly mornings. Quite something, then.
This privileged weather hasn’t kept away building codes to promote standards and construction methods that seal the indoors from the outdoors, and I can’t quite grasp why.
I used one of my errands during this “heat wave that never was” to notice the last relatively “tall” buildings going up in the area (it’s the West Coast, and therefore, nothing truly tall will get built outside a few downtowns from Seattle to San Diego). Despite the all-year mild temperatures of urban areas perched over the micro-climates influenced by the Pacific Ocean, they have succumbed to the same type of “efficient” construction.
But, is it efficient when it’s not “natural” and doesn’t foster well-being?
Modern buildings when power goes off
There are dire places in the US, and this has affected how everything is built, even in those places that can afford natural construction. Structures are designed by default to run AC 24x7x365, no matter where they are, and this has transformed architecture.
On the upside, they made life possible and relatively affordable in more unhospitable areas, relying most of the year on sealed environments regulated by central A/C. On the downside, they made the quality of life worse in places blessed by nice weather, turning our ability to acclimate to the year’s seasonal variations into one continuum that, when blended with poor design and off-gassing materials, has contributed to phenomena like the sick building syndrome.
When not completed with PV solar and expensive battery storage, places designed for 24×7 A/C become unbearable during blackouts. It took many Texans to experience many heat waves and one unexpectedly cruel cold wave in February 2021, exacerbated by blackouts, to understand that renewables and properly maintained off-grid setups can save lives—and prevent blackouts during moments of peak energy consumption or grid disruption due to the increasingly likely extreme weather events. The Great Texas Freeze was the best promoter of renewable energy that Texas, oil’s world capital, has ever had.
Back to the Bay Area. During my errand, I noticed two multi-story buildings going up five minutes from our place. The first one, an assisted-living retirement community in an urban environment, is a five-story metal-frame structure with a rationalist enclosure that is wrapped in a thin layer of fake brick; the other project is a “transit-oriented” development with 87 homes of different sizes, some of which are low-income homes, a very relative term in the Bay Area. This building is a wood-frame structure with its façade on two high-traffic streets; it has maximized its footprint and sacrificed the opportunity to create any greenery between the cars passing by and its equally fake facade.
Central HAVC system vs. old vernacular
Both buildings might be efficient, compensating their limited thermal mass with air tightness and advanced HAVC systems, hence inviting their residents to experience a climate-controlled environment that might make sense in most of the US territory experiencing the extremes, with scorching-hot warm months—most of the year now—and freezing winter. But the Bay Area isn’t Central Valley or the Mojave flats, and by designing the same climate-controlled timber-framed stucco boxes where the weather is mild and the air is clean all year round, you’re aiming at reducing people’s long-term quality of life.
Extraordinarily hot or cold days make us dependent on the controlled environments of our homes, cars, offices, and commercial spaces, whereas more efficient HAVC systems like heat pumps, as well as home improvements like better insulation, can ease our way out of such situations.
When we get used to the even thermostat all year round, we also become more dependent and forget about the ways that made vernacular construction more adequate for survival during local upheavals: homes in places prone to tornadoes and hot and humid climates can benefit from building techniques and standards than the ones better adapted for high altitude in the Rockies, high-desert plateaus battered by the monsoons, or the western regions battered by the extremes.
True: modern HAVC systems have transformed the way we live and build, turning places hardly suited for hosting big human populations into some of the most dynamic US metro areas, some located in deserts consistently surpassing the 100-degree-Farenheit (38 degrees Celsius) for at least one-third of the year. We’ve visited the Phoenix area several times and even seen some interesting templates of urbanism and walkability there, like Culdesac and Micro Estates, both in Tempe. However, the Sonoran desert won’t make it easy for people to stay out, walk, and bike everywhere all year round.
But learning from ancestral peoples living in similarly hot and dry places will help us make extreme weather more livable without the need to remain indoors: Culdesac has learned that narrow streets, combined with strategic use of plants, shades, and points of water to foster evaporative cooling, can drop the thermometer and turn hospitable a threatening place. Ancient towns in Southern Spain, Greece, Northern Africa, the Fertile Crescent, and Central Asia, among many others, used such techniques for millennia.
The brick-and-mortar cities that Europeans encountered
The construction vernaculars of yesteryear, which have to deal with a pre-AC world, adapted to locales by trying to compensate for climate extremes with higher thermal mass; in the American West, that often meant to emulate Native American vernaculars of seasonality and increase of thermal mass by building sunken structures, or developing dense, labyrinthine stone-and-adobe mega-structures against boulders and within deep canyons, a strategy to protect themselves against environmental extremes and attacks that resembles that of other ancient civilizations capable of thriving arid places, like the Nabateans from Petra, and the Andean and Central Asian civilizations depending on effective, lengthy irrigation systems for survival.
The complex network of irrigation systems and interconnected, dense towns that sustained dense Puebloan societies from around 1200 BCE to 1300 CE didn’t survive environmental upheaval, but the ruins of their towns did. They awed not only the descendants of the Anasazi, like the Hopi and the Zuni but also the first Europeans traveling through the area.
The Ancestral Pueblo people, also known as Anasazi, built permanent settlements in cities due to a severe drought confirmed by tree-ring data, as explained by Jared Diamond. The Puebloans built large buildings and kivas, which required sustained organized work and food production, as well as vast amounts of wood, which contributed to deforestation in the only viable groves of the region.
Wild animals might have become more scarce with the loss of riparian habitats. As conditions worsened, societies radicalized, as the evidence of later fortifications and burned settlements suggests.
The Anasazi may have also fought powerful external enemies, though civil unrest could have been a part of the mix that brought mighty cities from the Southwest to collapse. Today, in an exercise of selective amnesia, Americans, identifying themselves with only their post-Mayflower heritage, or sometimes with the post-Columbian one, identify the first American permanent cities with the first European settlements: in the US, St. Augustine (Florida, 1565), Santa Fe (New Mexico, 1607), Jamestown (Virginia, 1607), Plymouth (Massachusetts, 1620), New Amsterdam (NYC, New York, 1625).
An obsession forging exploration ahead: precious metals
Much earlier city dwellers in permanent settlers were Native Americans from Louisiana’s Poverty Point (1700-1100 BCE) and Mississippian cities like Cahokia near St. Louis (600-1400 CE). None of the ancient Native American cities was inhabited upon European arrival, and only the mysterious abandoned ruins of the Southwest, which somehow looked like the more familiar civilization ruins from the Old World, were recognized as remains rivaling the achievements of the Mesoamerican cities that the Spanish had found decades before.
When the first Spanish explorers showed up in the vast northern territories of New Spain, inhabited by what they described as proud and bellicose natives of what is nowadays the US’ Southwest, they used interpreters to try to convey their interests to locals: could they bring the strangely-dressed foreigners to places with many buildings and people, preferably those rich in precious metals, if there were any?
In 1539, a mere 18 years after Hernán Cortés took the city of Tenochtitlan, the capital of the Aztec Empire, with the decisive help of local indigenous groups such as the Tlaxcalans, Franciscan friar Marcos de Niza, one of the survivors of the Narváez expedition across Florida and the Gulf Coast territories, began exploring the American Southwest on behalf of Francisco Vázquez de Coronado, Governor of New Galicia. The Puebloan ruins impressed his party.
De Niza is credited with starting a legend about visiting Cíbola, a city made of gold. Like Marco Polo’s fantastic descriptions of the Far East, Fray Marcos de Niza relied on the towns of the Zuni peoples, a Puebloan group. When de Niza returned from the expedition to present-day Nayarit, he explained the wealthy cities they had seen up north—as wealthy and large, he explained, as Mexico City.
Vázquez de Coronado, convinced he had found the cities of Cíbola, or Seven Cities of Gold, invested money in a new expedition and tried to find them in 1540. All he discovered were pueblos constructed by the Zuni. His expedition was denied entry into many of the towns still inhabited by descendants of the Anasazi, like the Zuni and Hopi, which led them to attack locals. They discovered that the tribes were poor in precious metals, though they found out that a big river lay to the west.
The real bounty of the Seven Cities of Gold: lessons on bioclimatism
Three men from the expedition did indeed reach the Colorado, burying some supplies and a note in a bottle for future missions in the area. We can only imagine what impression the vision of the Grand Canyon may have caused García López de Cárdenas, the first European to peek over the 18-mile void carved by a tiny-looking river meandering down below.
It is a matter of wonder why these early expeditions never made it into a compelling movie or a Cormac MacCarthy-style novel. Later, as the Western Frontier expanded and the Mexican-American War redefined the southern border, the myths of Eldorado switched from Cíbola to mining. However, the admiration from the area’s native architecture puzzled chroniclers for generations.
Unlike the Chaco Canyon‘s Pueblo Bonito built below the boulders of a canyon and abandoned by ancestral Puebloans in the 12th century, the Acoma Pueblo (known as Sky City by the Acoma) emerged by the 13th century after the collapse of nearby cities and is still inhabited, making it one of the earliest continuously populated places in North America. Built on top of a 365-foot (111-meter) high mesa, the Acoma town of adobe worked as a fortress easy to defend from native incursions and Spanish missionaries willing to convert the area to Catholicism.
In 1540, Lieutenant Hernando de Alvarado from the expedition led by Francisco Vázquez de Coronado described the place from a European perspective:
“The village was very strong, because it was up on a rock out of reach, having steep sides in every direction… There was only one entrance by a stairway built by hand… There was a broad stairway of about 200 steps, then a stretch of about 100 narrower steps and at the top they had to go up about three times as high as a man by means of holes in the rock, in which they put the points of their feet, holding on at the same time by their hands. There was a wall of large and small stones at the top, which they could roll down without showing themselves so that no army could possibly be strong enough to capture the village. On the top they had room to sow and store a large amount of corn, and cisterns to collect snow and water.”
The town belonged to the landscape. It had been built with readily-available materials like adobe, rock, and low vegetation; easy to defend from invaders; adapted to the area’s arid climate with hot summers and freezing winters; and capable of resisting sieges thanks to big facilities to store corn harvests, as well as cisterns similar to those used by Bronze Age cities along the Mediterranean Basin, capable of keeping snow and water.
The paths taken in the desert (as seen from space)
Today, the place has over 300 dwellings, lacking electricity and modern sanitation networks. The two and three-story buildings are mainly made of adobe, with exterior ladders used to access the dwellings upstairs. Fewer than 50 tribal members live all year in the Acoma Pueblo, which also endures the same loaded blessing of picturesque destinations from the Mediterranean: tourism is a source of income but also one of disruption.
The first European explorers and hustlers of sorts who stumbled upon the mighty adobe-and-rock, highly conscientious and skilled Pueblos from the Southwest had at least one right intuition: They had evoked in them the riches of ancient Grand civilizations washed in gold and riches because the Anasazi structures were built to last and required centrally organized societies showing the discipline that had shaped the biggest empires.
“In the middle of the eleventh century, the stonework alone at each great house required hundreds of thousands of man-hours. Masons broke rocks into thin, workable tablets, laborers hauled baskets of wet mortar, and woodworkers stripped timbers and evened off their ends with stone axes before setting them into place. Parts of older great houses were demolished to make way for expansions, and thousands of tons of rubble went into the new foundations. At the same time, adjacent land was cleared for future construction.”
“Most of this activity took place in an area of about three square miles, known today as Downtown Chaco, a term coined by archaeologist Steve Lekson. It contains a couple of dozen residential compounds facing half as many great houses, as well as tidy processionals leading toward the center. Ten miles in all directions lies a looser halo of ten more great houses and numerous contiguous living quarters. Chaco, or at least parts of Chaco, keeps going from there. Ancient roads radiate from the canyon outward to meet satellite great houses scattered across the desert. The place was built like a web, drawing people and their artifacts to the center, Chaco Canyon.”
“Whether people living elsehwere on the Colorado Plateau were directly involved with the eleventh-century Chaco or not, they could not help being deeply affected by it. Year after year more travelers came from the hinterlands. They left tracks of broken pottery along the way—countless ceramic water pitchers and painted ollas dropped and shattered across the desert. The roads they stamped into the ground can be seen to this day from space. Chaco became the cultural center of the Colorado Plateau, and this it is the appropriate place to begin the story of the Anasazi.”
House of Rain: Tracking a Vanished Civilization Across the American Southwest, Craig Childs (2008), p. 17
Built to last (and to be comfortable with no A/C)
North America’s longest-living traditional building methods, which influenced the settlements built by the Spaniards, Mexicans, and Americans and helped kickstart the Pueblo Revival architecture that created the vernacular experiment that today is Santa Fe, New Mexico, relied in several techniques praised today by experts in sustainable construction.
There’s one big difference between the revival constructions being maintained and going up, and the old adobe, brick-and-mortar, and dry stone structures from the Puebloans: like it happens in Santa Barbara, California, or St. Augustine, Florida, the most recent constructions blend with the local heritage, though they are a cosmetic mirage: wipe the surface off and they are built the same way any stucco building gets built according to code in nowadays’ America.
Like in arid areas of Mesoamerica, the Andes, or the Old World, buildings erected by the Puebloans and their immediate descendants, benefited from resource-efficient design, well adapted to the aridity and extremes of the region.
Their orientation made them “passive solar,” like those of Mesa Verde, were they are facing south, maximizing solar heat gain during the winter (when the low angle of the sun would warm their homes) and retreating beneath the natural shade provided by overhanging cliffs when the sun was high in the sky on the summer months, which kept the buildings’ interior cool.
Thick walls and a layout set slightly below ground increased the constructions’ thermal mass. Stone plastered on the inside and adobe provided natural, local, easily repairable insulation, absorbing heat during the day and slowly releasing it at night, stabilizing indoor temperatures in a region where day-to-night temperature swings are often extreme.
What happened to the Anasazi?
Like the town of Petra in current-day Jordan, cliff dwellings and towns built under natural bluffs protected from harsh weather and extreme sun exposure. They were located near the same natural water sources that had carved the landscape: springs, streams, or seeps emerging from rock formations determined the very existence of dense populations amid arid land.
Materials were efficiently used. Not having the luxury of modern-day logistics and economies of scale, Puebloans used only locally available sustainable building materials. Their adobe (clay, water, and straw) was second to none and could compete with any natural plaster from Mesoamerica, the Andes, or the Old World. Sandstone was also pervasive and easy to work with.
Some pueblos, like those in Chaco Canyon, a wooded region at the dawn of the Puebloan civilization, used timber for roofing and beams; they carefully harvested their timber and used ingenious structural techniques.
But, as Jared Diamond suggests in his mention of the Anasazi in one of the chapters of Collapse: How Societies Choose to Fail or Succeed, water management was perhaps their biggest achievement and refinement, albeit the one that, once in jeopardy, may have caused their demise.
“Early in the twelfth century, things changed in Chaco. A hot drought rolled through—nothing out of the ordinary, but enough to tip the balance. Maybe the priests or governors who had promised rain and gotten it for centuries suddenly couldn’t deliver, still preaching at the sky, stomping their feet, but now dusty and ineffectual. Or the people’s focus merely shifted, the great houses of Chaco centuries old and not glimmering like they once did—at least not enough to rivet the attention of a nomadic people passing across the country. Chaco had grown beyond its canyon and sent out many tendrils. With the right combination of drought and timing, new great houes built in better-watered territory to the north began to prosper, stealing some of Chaco’s thunder.”
House of Rain: Tracking a Vanished Civilization Across the American Southwest, Craig Childs (2008), p. 73
Water engineering before the Columbian Exchange
The Puebloans developed check dams and canals to transport and save water; their terraced gardens resembled those of the ancient Fertile Crescent and Central Asia. This sophisticated water management guaranteed the high yields of corn, beans, or squash needed to sustain big populations over centuries. Unlike today, when water runoff becomes a problem instead of a potential advantage during the monsoons, the Anasazi built water storage systems to store rainwater for dry periods.
No two pre-Columbian pueblos developed by the Anasazi are identical: some went vertical, some profited from the advantages of terraced construction, and some regulated their indoor temperature by building sunken kiva-like constructions. Kivas were ceremonial buildings that integrated the tribe’s cosmogony and rituals; a small hole in the floor symbolized the tribe’s origin.
Puebloans formed complex societies and often inhabited large, communal dwellings hosting multiple rooms (hundreds of them in extraordinary cases, like the multi-story structure of over 600 rooms that once stood in Pueblo Bonito). Cohabitation reduced overall impact and may have guaranteed resources during moments of upheaval. It didn’t prevent such places, however, from being deserted centuries before the beginning of the Columbian Exchange.
The ancient Anasazi pueblos shock visitors with their organic integration within the landscape. Their adaptation to arid climate included rainwater-fed dry farming and agroforestry to improve soil quality, reduce erosion, and create microclimates to foster yields.
No matter their accomplishments and respect for natural cycles, most of their sites, occupied for hundreds of years, had left minimal environmental disruption amid ingenious urban grids that blend with the desert topography, as if they had emerged from the careful study of resources in an arid world where there’s little to share.
Houses of rain: a landscape being washed to the sea
Craig Childs’ “House of Rain” is the most compelling book about the rise and demise of the Puebloans and their dwellings. I happen to be reading it now, and it inspired this post. Childs explains that many cities were gradually abandoned, and the Anasazi didn’t die out but migrated, assimilated into Spanish missions, or joined less sedentary lifestyles as aridity, desertification, and external threats advanced.
“And here lies the most common misconception about Chaco—the idea that it collapsed, that the Anasazi failed. Certainly, the canyon itself was not forgotten, nor was it ever entirely abandoned. Great houses saw occasional renovation and additions; the great kivas of Pueblo Bonito were refurbished with new paint and artifacts around the beginning of the fourteenth century. Any architecture added after the mid-twelfth century was modest, a step down from what had come before, but the place didn’t collapse. People’s attention simply moved elsewhere, putting Chaco on the back burner.”
House of Rain: Tracking a Vanished Civilization Across the American Southwest, Craig Childs (2008), p. 74
“Perhaps this was why the Anasazi had moved. They had followed the smell of water, aware of the rains slipping away year by year, retreating from them into the northern highlands. Although there are signs of turmoil at Chaco, the end was probably not as catastrophic and unexpected as many think. It was a predictable end, a routine drought leading people away. At first people may have begun to leave Chaco by rooms, and then by clans, and then by whole villages. Only itinerant households remained in what had once been the triumphant center of the Anasazi world.”
House of Rain: Tracking a Vanished Civilization Across the American Southwest, Craig Childs (2008), p. 76
Two hundred years from now, the ruins from Chaco Canyon will still stand gracefully in the place they were erected and shaped out of the same forms and materials surrounding them, reminding us of our own ability as a species to create patterns and the illusion of order emerged out of chaos, conquering entropy, if only temporarily.
One question we could ask ourselves is how the ruins of today’s stucco houses going up in the desert not far from Chaco Canyon will stand time and upheaval. For fake stucco or brick and formaldehyde-rich insulation and glued structures don’t belong to a place like adobe and natural plaster can.
“Several million tons of sediment depart from the Southwest every day, carried in warm, muddy rivers toward the nearest sea. The entire landscape is falling apart, too dry to hold on to its soil, too weathered to remain solid. In 1941 a 300,000 ton slab of canyon wall toppled into the back of the largest of Chaco’s ruins, crushing numerous rooms and throwing boulders into ceremonial chambers, where they remain today like rough-edged meteorites. What you see in the Southwest is temporary, everything caught in motion.”
House of Rain: Tracking a Vanished Civilization Across the American Southwest, Craig Childs (2008), p. 19